1. Field of Invention
The present invention relates to a surface-emitting type semiconductor laser, an optical module and an optical transmission device.
2. Description of Related Art
A surface-emitting type semiconductor laser has characteristics in which its light output varies depending on ambient temperatures. For this reason, in some cases, an optical module that uses a surface-emitting type semiconductor laser may be equipped with a photodetector function that detects a part of laser light emitted from the surface-emitting type semiconductor laser to thereby monitor light output values. For example, a photodetector section such as a photodiode or the like may be provided in a surface-emitting type semiconductor laser, such that a part of laser light emitted from the surface-emitting type semiconductor laser can be monitored within the same device as disclosed in related art document Japanese Laid-open Patent Application H10-135568. However, when a photodetector section is provided within a surface-emitting type semiconductor laser, the degree of freedom in selecting structures may be lowered because the structure of the surface-emitting type semiconductor laser is limited, in view of polarity of each of the layers that compose a section that contributes to generation of laser light (i.e., a light emitting element section) and the photodetector section, and the structure of the light emitting element section and the photodetector section.
Surface-emitting type semiconductor lasers can be driven at high-speeds, and by taking advantage of this characteristics, they are adopted in electronic devices and optical communication systems. Accordingly, operations at high speeds are also demanded for a surface-emitting type semiconductor laser equipped with an photodetector section.